Added new "Active" state to PushButton class
Active state used in MenuToggleButton class.

Active => Pressed + Flyover

When hovered in Active state, Active => Flyover only

Change-Id: Iece1550b6d742a7ab3c9f4c7516ec855e1a1b6ef
Reviewed-on: https://gerrit.libreoffice.org/26470Reviewed-by: Akshay Deep <akshaydeepiitr@gmail.com>
Tested-by: Akshay Deep <akshaydeepiitr@gmail.com>